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W. S. HARRISON.

TELEPHONIG APPARATUS. No. 609,530. Patented Nov.-28, 1893.

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UNITED STATES PATENT OFFICE.

WILLIAM STUART HARRISON, OF HONG-KONG, CHINA.

TELEPHONIC APPARATUS.

SPECKFIGATION forming part of Letters Patent No. 509,530, dated November28, 1893.

Application filed December 13, 1892. Renewed October 5, 1893. Serial No.4871296. (No model.)

.To all whom it may concern.-

Be it known that I, WILLIAM STUART HAR- RISON, electrician, a subject ofthe Queen of Great Britain and Ireland, residing at Praya Central,Hong-Kong, China, have invented certain new and useful Improvements inTelephonic Apparatus, of which the following is a specification.

This invention has primarily for its object, the application of a singlefluid cell to provide the current for the microphone circuit intelephonic apparatus, and secondarily the elimination of a switch,subsequent upon such application.

In applying the invention, a battery or cell is employed, in which thezinc, or other electro-positive element, is inserted in or withdrawnfrom the exciting solution, through a lever or system of levers,actuated by taking the receiver off the hook or replacing it, or by anyother method whereby the electro-positive element is inserted in theexciting solution only during the period in which a current is requiredthrough the microphone. The connecting Wires are so arranged that thewithdrawal of the electro-positive element from the solution, takes theplace of a switch in arresting the said current through the microphone.

The accompanying drawing, which forms a part of my specification,represents diagrammatically a complete telephonic apparatus, arranged inaccordance with my invention.

The form of battery which is found to answer well for the purposes ofthe invention, consists of a jar J, of glass or other suitable material,half filled with a solution J of hichromate of potash and sulphuricacid, in which a carbon plate K about one andthreefourths inches wideand one-half an inch thick, and preferably composed of what is known asretort carbon, is suspended permanently. This plate carries at its top alead cap K, which is cast on a brass terminal K From this terminal awire P is led direct to the primary coil of an induction coil E, andfrom thence the wire P leads through the microphone H to the lever Dfrom the end of which is suspended the zinc element L. The latterconsists of an amalgamated zinc rod, threeeighths of an inch indiameter, inserted in the solution,when the battery is put in action, to

a depth of one and one-half inches and dis tant from the carbon plateabout one and onehalf inches, the latter being permanently immersed to adepth of two inches. A battery so prepared has an internal resistance ofabout six ohms, and an electro-motive force of approximately two volts,and is upon the whole eminently adapted to the required purpose, asingle cell being all sufficient with any of the various forms ofmicrophonesatpresentin use.

'llhe microphone shown at H, is merely symbo ic.

A is the receiver, hung on the forked end of the lever D, which ispivoted at D and connected to the lever D pivoted at D" by'the link d,so that the weight of the receiver lifts the zinc L out of the solution,and this movement throws the battery out of action and serves thepurpose of a switch to break the circuit through the microphone. Whenthe receiver is taken off the hook, the zinc drops into the solution,the battery comes into action and the circuit through the microphone isclosed.

F is the magneto alarm bell, the permanent magnet not being shown, and Gis the ma neto generator, the driving gearbein g omitted.

In the position of the parts shown on the diagram with the receiver onthe hook, the battery is out of action and consequently the microphonecircuit inoperative, while the magneto generator G and bell F are put toline through the switch B. When the receiver is taken oif the hook,contact is broken at B and the generator and hell out out, while thereceiver and secondary coil S S of the induction coil E, are put to linethrough the switch 0.

It is not intended to limit the battery to the use of a bichromate ofpotash and sulphuric acid, or a chromic acid solution, and the carbonmay either remain permanently in the solution, as described, or may bewithdrawn simultaneously with the zinc, and any form of battery may beused in which either one or both of the elements can be withdrawn in anysuitable manner when the current is not required.

The main advantages of the invention are as follows: It is lessexpensive to set-up a cell of the kind above described than a Leclanch,as commonly used for telephonic purposes,

this being especially the case where its high electro-motive force andlow internal resistance permit it to replace two Leclanch cells, whichare frequently required with the pencil forms of microphone. For theproduction of the intermittent currents required in telephony, this cellis much more durable than the Leclanch. There is positively no localaction taking place when the cell is not in use, and three times thequantity of current is obtained from a given quantity of zinc, when usedin this manner, than is the case with the Leclanch cell, while theunusually low internal resistance, before mentioned, allows themicrophone to act more directly upon the current strength. The processof recharging is much simpler and occupies less time than with theLeclanch, as it consists simply in replacing the spent solution by newand, when necessary, replacing the zinc rod.

The switch, which is dispensed with by means of my invention, is the onewhich gives the most trouble in practice, chiefly on account of thesparking which takes place, every time the circuit is opened.

The invention may readily and at trifling expense be applied to thegeneral types of telephonic apparatus, as at present constructed and inuse.

Having now described my invention, what I claim as new, and desire tosecure by Letters Patent, is

In telephonic apparatus, a battery or cell J, inserted in the circuit ofthe microphone H, the zinc or electro-positive element L suspended troma lever D said lever being connected with a lever D, by a link 01 sothat when the receiver A is hung on the lever D, the element L iswithdrawn from the solution J, the cell thrown out of action and themicrophone circuit broken, and when the receiver is taken off, theelement L'drops into the said solution and the said circuit is closed,substantially as set forth.

In Witness whereof I have hereunto set my hand in presence of twowitnesses.

W. STUART HARRISON.

Witnesses:

THOMAS ARNOLD, L. KENNARD DAVIS.

